The present invention is particularly useful in catheters that remain in place within a blood vessel for an extended period of time, such as weeks or months. Such catheters are left in place to nourish patients who cannot be fed by mouth, or, more frequently, to administer chemotherapeutic drugs to treat cancer.
A catheter left on its own within a blood vessel tends to rest its tip against the vessel wall. This causes mechanical irritation of the vessel wall. In addition, the delivery of chemotherapeutic and other drugs against the vessel wall often causes inflammation and eventual thrombosis (clot formation) in the blood vessel. If the catheter tip is close to or in contact with the wall of the blood vessel where the flow is much slower, the undiluted chemicals delivered against the frail endothelial lining of the blood vessel will irritate it and set up local inflammation and thrombosis.
Conversely, if the catheter tip is at the center of the blood vessel, it is positioned at the axis of flow where flow is faster and chemicals delivered by the catheter tip are better mixed with blood and carried away from the wall faster. The chemical agents are also delivered at the greatest distance possible from the walls, that is, at the center of the blood vessel.
What is proposed by this invention is to maintain the catheter on the axis or center of flow in the blood vessel by use of a centering wire. Preferably, the centering wire is a flexible member having in its natural, free state condition a coiled, pigtail-like distal end portion. The centering wire is longitudinally slidable in a channel to an operative position in which the distal end portion projects from a channel outlet and assumes its natural, coiled condition in contact with the interior wall of the blood vessel. Preferably the coil at the distal end extends in an arc of 3600. The coil is sufficiently flexible to expand and contract as needed, depending on the inside diameter of the blood vessel.
One object of this invention is to provide a centering wire for supporting an intravascular catheter in a blood vessel having the foregoing features and capabilities.
Another object is to provide a centering wire for supporting an intravascular catheter within a blood vessel which is durable and long lasting in use, and is capable of being inexpensively manufactured and easily manipulated.
These and other objects, features and advantages of the invention will become more apparent as the following description proceeds, especially when considered with the accompanying claims and drawings.